1. Field of the Invention
The present invention relates to a cutter assembly, and more particularly to a cutter assembly having two locking devices.
2. Description of Related Art
A retractable cutter substantially comprises a blade holder, a blade and a slider. The slider is mounted on the blade holder. The blade is mounted slidably in the blade holder and is connected to the slider. When the slider is pushed, the blade is moved relative to the blade holder to extend out of the blade holder to enable a user to cut an object by the cutter. For use of holding the blade at a desired position with a desired extension length relative to the blade holder, a locking device is mounted on the slider. The conventional locking devices include two different types, an automatic locking device and a screw locking device. The conventional automatic locking device substantially comprises an engaging block and a spring. Multiple engaging teeth are formed on the blade holder, are arranged in a line and selectively engage the engaging block. When the slider is pushed, the engaging block can be disengaged from one of the engaging teeth to enable the blade to move relative to the blade holder. When the blade is moved to a desired position, the engaging block will engage one of the engaging teeth by the force provided by the spring. Thus, the blade can be positioned with a desired extension length relative to the blade holder. Alternatively, the conventional automatic locking device may comprise a single resilient tab.
The conventional screw locking device substantially comprises a bolt mounted on the slider. When the bolt is rotated to make the bolt abut against an inner surface of the blade holder, the slider can be positioned relative to the blade holder. When the bolt is released, the slider is moveable relative to the blade holder to adjust the extension length of the blade relative to the blade holder.
However, although the conventional automatic locking device is convenient in use, the engaging force between the engaging block and the engaging teeth in the blade holder is not sufficient. Therefore, a cutter having the conventional automatic locking device can only be applied to cut a thin object, such as paper, and cannot be applied to cut a thick object. In addition, although a cutter having the conventional screw locking device can provide a sufficient locking force to the blade for cutting a thick object, the screw locking device has to be rotated for unlocking and relocking each time when the extension length of the blade is adjusted. Thus, the conventional screw locking device is not convenient in use.
To overcome the shortcomings, the present invention tends to provide a cutter assembly to mitigate or obviate the aforementioned problems.